I'm peter from Belgium and I like to ask a question about my Suburban.
I want to adjust the ignition timing but I don't know how many degrees BTDC.
In the books I have, they say check emissions label, but there isn’t any on my Suburban.
It’s a Suburban 1993 350 V8 TBI

Hi Peter, welcome to the club!
I'm fairly certain that the timing for your engine is 4Deg BTDC.
There should actually be a label on your air cleaner that tells you the details for your ignition timing.

That works out to 10Gal / 62Miles (for those of us on the SAE, so we can relate)
Which is about 6 miles to the gallon, or 2.63 km per Litre.

OUCH!

Can you give us some more details?
How many km on suburban?
How long since last tuneup?
Where is the loss of power? (Light accelleration, heavy accelleration, throughout entire throttle)
Does the engine idle smooth or roughly?
Oversized tires/tyres?
Any vehicle mods, or completely factory?

There aren’t any modifications made, except removal of the catalyst.
The tire size is a little bit taller than stock, but not too much. :roll:
For the rest is everything stock on the engine.
It has 160000 miles on it
The automatic gearbox has an electronic shiftimprover.

Yesterday my check engine light came one giving me code 44 (lean exhaust)
How is this possible with this high usage of fuel?
:shock:

You might want to try changing out the O2 sensor (this is a single wire sensor, and the wire is usually black on that model year). it's located just past the Y in the exhaust pipe. If it's the factory sensor, it's going to be tough to get out of there. The sensor itself doesn't cost much since it's not a heated unit. So it's a fairly inexpensive place to start, and probably the only thing that's wrong with it.

Normally they make a special socket with a slot up the side for those kind of sensors, but if you have trouble getting it out, you might have better luck with a small pipe wrench, but definately use the socket to put the new one in.
Don't forget to put anti-sieze on the new sensor for the next time. 8)

I had an O2 sensor go out 3 years ago in a diff vehicle and it was amazing how it affected gas mileage. You would think the engineers would understand that these things go out and they would compensate better for the lack of information coming back into the engine!